The present invention relates to a yarn processing system including a computerized control and monitoring network arrangement.
In such a yarn processing system (U.S. Pat. No. 5,323,324 A) a computerised control and monitoring system is used for the different yarn channels. Said system comprises a two line message transmission bus to which all participants are connected. In the network, messages are transmitted which are ranked by different priorities so that messages of highest priority will be transmitted first. A digital communication protocol with standardised mechanical features is used. However, in addition to the message transmission bus and the respective connection of all the participants to said bus, separate DC-power supply lines are provided for the respective participants needing DC-power for operation. In case of a considerable number of yarn channel DC-power lines and the message transmission bus cables still create a large number of vulnerable spots where mechanical damage can occur.
In a terminal unit of an information transmission system according to EP 0 316 536 A2 a serial transmission of an AMI (alternate mark inversion mode) coded baseband signal is superposed on the supply voltage by using the power supply line for signal transmission and power transmission. A polarity detecting and polarity switching circuitry is employed to attain a non-polarised transmission connection.
DE 44 25 250 C1 discloses an arrangement for transmitting power and data on a two line bus. Two different information carriers are used in order to attain a simultaneous bi-directional data communication. Said information carriers are voltage and current. Data emitted from the electronic devices is available in the bus in the form of current signals. The bus master device emits voltage signals.
It is an object of the present invention to simplify a yarn processing system of the kind as disclosed in order to minimise the cabling, particularly in case that a considerable number of DC-power supply participants along the yarn channels towards a textile machine also need to communicate at least with one control unit by electronic signal messages for controlling, monitoring, supervising, measuring, acting or reacting purposes.
In the yarn processing system according to the invention any separate signal or message transmitting cables are omitted. Instead, the conductive part of the common power supply line is used as the combined message transmission path for the participants in the network. Said measure is reducing the number of cables to a minimum and as such is considerably reducing the potential danger of mechanical damage to cables. Furthermore, particularly in case of a yarn processing system having a plurality of yarn channels and a corresponding large number of network participating electronic devices, the cabling is simplified and reduced to the necessary minimum. Said minimum is the common power supply line itself connecting all participants to the DC-power supply as necessary for the correct function of all the devices and of the control unit. Despite omitting separate message transmission paths the participant in the network can communicate reliably and fast, however, not on separate structural message transmission lines, but directly on the conductive part of the power supply line, because it has been found that the conductive part of a DC-power supply line as intended for effecting DC-power supply surprisingly also can be used for transmitting electronic signal messages carried by frequency modulated radio frequency carrier waves without any danger of interference and with the particular advantage of the already efficient shielding of the conductive part of the power supply line, e.g. against electric or electronic noises or magnetic fields. Due to only the minimum of cabling the danger of mechanical damage is reduced significantly, the reliability of the message transmission is enhanced by using frequency modulated radio frequency carrier waves, as well as the quality of the message transmission. Additionally, no cabling preparation of the yarn channels for the message transmission is needed.
Embodiments of the invention will be described with the help of the accompanying drawings.